Project 1 of this Program will address the role of altered albumin and the maleyl-albumin receptor as a general mediator of phagocyte recruitment. The hypothesis that in vivo modification of LDL leads to recognition by the scavenger receptor (acetyl-LDL receptor) will also be tested. In Project 2 the cDNA for the human scavenger receptor will be isolated, sequenced and used to quantitate receptor mRNA levels. The mechanisms regulating the intracellular distribution of free cholesterol in human monocyte-macrophages will be studied, and the hypothesis that bacterial lipopoly-saccharide- lipoprotein complexes play a role in atherosclerosis will be tested. Project 3 will isolate and characterize both a chemotactic factor and an inhibitor of monocyte chemotaxis which are produced by endothelial cells. The mechanisms regulating transendothelial macromolecular transport including monocyte adherence and diapedesis will be studied in Projects 3 and 5. Project 4 will utilize a new in vitro system to determine the mechanisms by which lipoproteins are retained in the artery wall, the receptor recognition of these lipoproteins, and the mechanisms of monocyte conversion to foam cells in the subendothelial space. Project 5 will use ultra-rapid freezing without chemical fixation for freeze- fracture studies to determine the details of the association of lipoproteins and/or lipids with the extracellular matrix in the artery wall. The three dimensional structure of the endothelial glycocalyx in its "native" state and the structural interactions of the glycocalyx with monocytes and lipoproteins will also be characterized. Project 6 will utilize the mouse model to analyze the genes for trans-acting factors regulating cholesterol biosynthesis. These genes will be characterized, mapped, and isolated, and the hypothesis that alleles of HMG-CoA reductase or HMG-CoA synthase are associated with altered plasma cholesterol levels in humans will be tested. In Project 7 the factors that bind to the promoters for the rat genes HMG-CoA reductase, HMG-CoA synthase, and CR-39 will be isolated, and their role in the control of transcription and coordinate regulation of these genes determined. Other studies will seek to understand the marked differences noted among adjacent normal rat hepatocytes for the expression of the key cholesterogenic enzymes. This Program Project presents an integrated approach to the problem of atherosclerosis utilizing biochemical, cell biology, genetic, molecular biology, and state-of-the-art ultrastructural strategies.